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Thought I would share this lab report. This SLK is 26 months old and the oil has been changed at approximately 6500 mile intervals. Oil consumption is nil. I still have the oil from the last change and plan to weigh it an compare it to the value expected per the MB oil consumption test.
 

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Founding Member #2 2008 SLK55 AMG
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thanks for the report fgwinn. Do report back on your experience.
 

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I will definitely report back when I determine the weight of the oil removed at the last oil change. Does anyone know the target net weight for the oil? I saw it once on the procedure for the oil consumption test, but, that was some time ago and I have misplaced that document. If someone has the info handy I would appreciate it.

thanks for the report fgwinn. Do report back on your experience.
 

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I will definitely report back when I determine the weight of the oil removed at the last oil change. Does anyone know the target net weight for the oil? I saw it once on the procedure for the oil consumption test, but, that was some time ago and I have misplaced that document. If someone has the info handy I would appreciate it.
PM bclark. I'm fairly certain he still has the documents on oil consumption on file.
 

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Oil consumption calculation

I calculated my "oil consumption" between oil changes today. I will be the first to admit that there are plenty of opportunities for error. But overall I am satisfied that my SLK350 is using very little if any oil.

First some background. My SLK350 is just over two years old. I have completed two oil changes. One at about 6500 miles and the second at close to 13000 miles. In my case the one year interval is the basis for the oil change rather than the mileage.

The first time I changed the oil, I raised the car at all four corners to keep it level. I used a Mityvac (air compressor model) to suck out the oil. Then I removed the drain plug to check if there was any remaining oil. A puddle about four inches in diameter coated the bottom of a small metal pan. In other words, I got almost no additional oil through the drain plug.

I refilled the engine with 8.5 quarts of Mobil-1 0w-40 oil. I used the marks on the last 1 quart container to estimate 1/2 quart. I also did not weigh the new oil containers before and after they were emptied. This is the first opportunity for error.

When I changed the oil a few weeks ago I only used the Mityvac and did not bother to remove the oil drain plug. The *volume* of oil measured just over the 8 liter mark on the Mityvac container (about 8mm above the 8 liter mark) with the oil at operating temperature. Today when I weighed the oil it was at least 20mm lower than when I drained it. This is due to the fact that it is only about 20 degrees F in my garage. This is the reason that MB weighs the oil rather than measure the volume for the oil consumptions test.

I added about 120ml of oil to the drained oil to compensate for the sample I sent to Blackstone Labs. I wrapped the filled Mityvac in a large black plastic bag and took it to the automated mailing station at the local Post Office to determine the total weight. I recommend doing this during non-business hours to avoid as many people as possible.

Next step was to dump the oil at the auto store recyling container and then head back to the Post Office to determine the tare weight of the Mityvac. It would have been nice to have weighed the Mityvac when it was new out of the box. There is alway a little trace of oil in the Mityvac after emptying it. This is another opportunity for error. If you decide to do a similar calculation, don't just accept the tare weight for my Mityvac. Weigh your specific unit.

The net weight of the oil according to the MB consumption test bulletin is 14.95 pounds. The scale I used read in pounds and ounces, so I converted the weights to decimal equivalents for ease of calculation.

19.6375 pounds = Total weight of Mityvac and drained oil.
-4.9375 pounds = Empty weight of Mityvac.
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14.7000 pounds = Weight of drained oil.
+0.2500 pounds = "Oil consumption"
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14.9500 pounds = Target weight of 8 liters of oil.

14.95 divided by 8 liters = 1.86875 pounds per liter. The unaccounted for difference of 0.25 pounds of oil comes to 134ml (0.25 / 1.86875). Given the opportunities I had to introduce errors into the measurement process, I would consider 134ml the equivalent of no consumption at all.

Unfortuanately, I did not weigh the oil I used to refill the engine when I changed the oil a few weeks ago. I will probably do that on the next oil change and then do a more precise comparison when I change the oil just before the warranty expires in late 2008.
 

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PM bclark. I'm fairly certain he still has the documents on oil consumption on file.
ETYU: I actually never received the exact data, only that my oil
consumption met criteria for engine replacement. BTW, just got
back from skiing Vail for 9 days. Exhilarating! Probably much
like driving an SLK 55 at 120+ mph (I wouldn't know but sounds
like you might soon have the chance);)
 

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Founding Member #2 2008 SLK55 AMG
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ETYU: I actually never received the exact data, only that my oil
consumption met criteria for engine replacement. BTW, just got
back from skiing Vail for 9 days. Exhilarating! Probably much
like driving an SLK 55 at 120+ mph (I wouldn't know but sounds
like you might soon have the chance);)
keeping my fingers crossed. :)
 

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Your report shows very low wear metals. That is good but don't count on it as meaning you don't or can't have problems. Those tests measure particles in the 1 - 10 micoron range very well. Larger wear particles won't show up. If you will sample the oil consistanly then it will give you a much better picture of what is happening in the engine. And the converse it true as well, a one time 500 ppm of iron in a sample doesn't mean your block in melting down either. But you would want to take notice obviously.

STLE: Certified Lubrication Specialist
 

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Your report shows very low wear metals. That is good but don't count on it as meaning you don't or can't have problems. Those tests measure particles in the 1 - 10 micoron range very well. Larger wear particles won't show up. If you will sample the oil consistanly then it will give you a much better picture of what is happening in the engine. And the converse it true as well, a one time 500 ppm of iron in a sample doesn't mean your block in melting down either. But you would want to take notice obviously.

STLE: Certified Lubrication Specialist
Thanks, that's good to know. But as the initial post is some two and a half years old, the information is perhaps useful in a more general sense. Thanks for the insight..:tu:
 
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